The invention relates to a method for operating a motor vehicle having an engine.
U.S. Pat. No. 5,219,413 A and GB 2 424 505 A disclose that, when the engine is running, it is checked according to a first predetermined criterion whether a driver of the motor vehicle is present, that is to say in particular is seated on the driver's seat of the motor vehicle. When absence of the driver is detected an automatic shut-off of the engine takes place.
The previous implementations of this method have the disadvantage that in many situations a shut-off of the engine takes place even if this is not actually desired. A typical case here is scratching away ice after an initial start: the driver of the vehicle enters the vehicle, starts the engine and then leaves the vehicle again in order to scratch ice away from the windows of the motor vehicle. It is actually desired here that warm air generated by the heating engine assist the removal of the ice. Depending on the climatic conditions, an initial start can also be intentionally initiated by the driver in order to prepare for a subsequent journey with the motor vehicle by facilities in the vehicle—for example the engine can be allowed to warm up or through a stationary-state air-conditioning system it is possible to ensure that the passenger compartment is heated up (or conversely cools down). Under certain circumstances, a battery of the motor vehicle is also to be heated up.
It may also be the case that the driver of the motor vehicle stops in front of a garage in order to open it but that he does not want the engine to be shut off. In the case of automatic shut-off of the engine, he would then initiate a restart, but the engine would be shut off again immediately.
WO 2006/027514 A1 discloses methods in which the engine is shut off automatically when the driver leaves the motor vehicle. In order to avoid resulting dangerous situations, WO 2006/027514 A1 describes a method for prohibiting the automatic shut-off of the engine of a motor vehicle when a driver is absent. In this method, when the engine is running and absence of a driver is detected the engine is not shut off automatically. Furthermore, when the engine is shut off and absence of a driver is detected the engine is switched on automatically. If the driver is absent for a minimum time period, the engine can nevertheless be shut off automatically. There is provision that after this automatic shut-off the engine cannot be started again automatically, but a starting code has to be input.
DE 10 2007 009 870 A1 describes a method for automatically controlling a switch-on and/or deactivation process of an internal combustion engine of a motor vehicle by a start/stop device with the inclusion of various criteria such as, for example, the presence of the driver or the activation of a cruise control system.